Are Knee Injections Safe? Side Effects You Should Know

Are Knee Injections Safe? Side Effects You Should Know

Knee pain is a common condition that affects millions of people worldwide, often stemming from arthritis, injury, or general wear and tear. As non-surgical treatments grow in popularity, knee injections have become a frequently recommended option for managing chronic or acute knee discomfort.

These injections can provide substantial relief, but are they truly safe? What are the risks, and how do you weigh the benefits against potential side effects?

The safety of knee injections, the different types available, and the side effects you should be aware of before undergoing treatment.

What Are Knee Injections?

Knee injections involve the administration of medication directly into the knee joint to reduce inflammation, relieve pain, and improve mobility. The most common types include:

Corticosteroid injections – These are anti-inflammatory drugs often used for arthritis or acute injury-related inflammation.

Hyaluronic acid injections – Often used for osteoarthritis, they aim to supplement the joint’s natural lubrication.

Platelet-rich plasma (PRP) injections – These use a patient's own blood components to potentially speed healing and reduce inflammation.

Stem cell therapy – An emerging treatment using stem cells (usually derived from bone marrow or fat) to promote tissue regeneration.

Ozone therapy or prolotherapy – Alternative treatments aimed at stimulating healing via mild irritation or oxygen-ozone gas.

Each type of injection comes with its own profile of risks, benefits, and safety considerations.

Are Knee Injections Safe?

Generally speaking, knee injections are considered safe when administered by qualified medical professionals under sterile conditions. Most complications are rare and minor. However, the safety largely depends on:

The type of injection

·       The frequency of administration

·       Your overall health condition

·       The skill of the practitioner

Let’s break down the common injections and assess their safety.

1. Corticosteroid Injections

Safety: Well-established, commonly used for decades
How they work: Reduce inflammation quickly, often providing relief within days
Frequency limit: Usually no more than 3–4 times per year per joint

Side Effects:

Joint infection (septic arthritis): Rare but serious; occurs in about 1 in 10,000 to 1 in 50,000 cases

Post-injection flare: Temporary worsening of pain

Joint damage: Repeated injections may weaken cartilage over time

Elevated blood sugar: Especially concerning for diabetic patients

Skin discoloration or fat atrophy: Possible at the injection site

Bottom line: Effective for short-term relief, but not recommended for long-term or frequent use due to potential cartilage damage.

2. Hyaluronic Acid Injections (Viscosupplementation)

Safety: Generally safe but results are mixed
How they work: Mimic synovial fluid to improve joint lubrication
Best for: Mild to moderate osteoarthritis

Side Effects:

Swelling or stiffness in the joint: Usually temporary

Allergic reactions: Rare, but can occur especially in people allergic to chicken or bird products (some formulas derived from rooster combs)

Joint infection: Very rare

Pain at injection site

Bottom line: A safe option for those with early-stage osteoarthritis, although some studies question their long-term effectiveness.

3. Platelet-Rich Plasma (PRP) Injections

Safety: Considered low risk, but not FDA-approved specifically for knees
How they work: Uses patient’s own platelets to stimulate healing
Best for: Younger patients or early arthritis

Side Effects:

Mild swelling and soreness: Typically self-resolving

No serious long-term risks reported in current studies

Infection risk: Still present, though very low with sterile technique

Unpredictable effectiveness: Some patients see great results; others do not

Bottom line: Promising treatment with a strong safety profile, though more long-term data is needed.

4. Stem Cell Injections

Safety: Still under research; less regulated
How they work: Aim to regenerate damaged cartilage and reduce inflammation
Best for: Younger patients or those seeking alternatives to surgery

Side Effects:

Infection or contamination: Higher risk in poorly regulated clinics

Lack of standardization: Treatments vary widely

No guarantee of efficacy

Ethical and regulatory concerns: Especially when stem cells are harvested from sources other than your own body

Bottom line: Emerging treatment with great potential, but caution is advised. Only consider in reputable medical settings or clinical trials.

5. Prolotherapy and Ozone Therapy

Safety: Alternative therapies, less studied in mainstream medicine
How they work: Inject irritating substances or ozone gas to stimulate healing
Best for: Tendon or ligament injuries, some chronic pain cases

Side Effects:

Pain and swelling: Common and part of the intended response

Infection: As with all injections

Limited clinical evidence: Efficacy and safety not well established in large-scale studies

Bottom line: Some patients report good results, but these therapies should be approached with caution and performed by licensed professionals.

General Side Effects of Injections

While side effects depend on the type of injection, some common ones across all procedures include:

·       Pain or discomfort at the injection site

·       Mild swelling or bruising

·       Temporary increase in joint pain

·       Risk of infection

·       Allergic reactions (rare)

The vast majority of these effects are temporary and resolve within a few days.

When Should You Avoid Injections?

Injections might not be appropriate if you:

·       Have an active infection anywhere in the body

·       Are immunocompromised or have poorly controlled diabetes

·       Have a bleeding disorder or are on blood thinners

·       Have a history of allergic reactions to injection substances

Always disclose your full medical history to your doctor before undergoing an injection.

Are They Worth the Risk?

For many people, injections provide meaningful relief and help delay or even avoid surgery. When used appropriately, especially in early to moderate cases of arthritis or injury, the benefits often outweigh the risks. However, they are not a permanent fix and should be considered as part of a broader treatment plan, including physical therapy, weight management, and lifestyle modifications.

Final Thoughts

Knee injections are generally safe and effective for managing various knee conditions, especially when administered properly by trained healthcare professionals. Like any medical treatment, they come with potential side effects, but serious complications are rare. Understanding your options, knowing what to expect, and discussing concerns with your doctor can help you make an informed decision tailored to your needs.